Circuit interrupter



CIRCUIT INTERRUPTER 2 Sheets-Sheet 1 Original Filed Sept. 2.7, 1942 INVENTORS wmf/1mg /Vl eedf 2 enjam/n Ba/rer Aug. 24, 1948. l w. M. LEEDS Erm. 2,447,949

CIRCUIT INTERRUPTER original Filed sepi. 17, 1942 2 sheets-sheet 2 Mayr/tio E (124 Mater/'al WITNESSES: M TVENTORS A" l/l//n rop feds @wf gf@ Benja/gm Baker Y 2a.- /e im? ATTORNE Patented Aug. 24, 1948 CIRCUIT INTERRUPTER Winthrop M. Leeds, Wilkinsburg, and Benjamin P. Baker, Turtle Pa., aasignors to West- Creek, inghonse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania y Original application September 17, 1942, Serial No. 458,860, now Patent No. 2,385,008, September 18, 1945. Divided and this application Jannary 27, 1945, Serial No. 574,858

21 claims. (ci. zoo-15p) This invention relates to circuit interrupters in general and. more particularly, to circuit interrupters which effect arc extinction by a blast of arc-extinguishing iluid.

This application is a division of United States patent application filed September 17, 1942, Serial No. 458,660, now U. S. Patent 2,385,008, issued September 18, 1945, entitled Circuit interrupter, by Winthrop M. Leeds and Benjamin P. Baker, and assigned to the same assignee as the instant application.

An object oi' the present invention is to provide an improved arc-extinguishing structure in which a pressure-generating arc and an interrupting arc are established and which provides a more effective flow of arc-extinguishing fluid from said pressure-generating arc t said interrupting arc to effectively quench the latter.

Another object is to provide an improved circuit interrupter in which an interrupting arc is drawn within a narrow elongated arcing slot, said arcing slot having improved venting means disposed along one side thereof, and to hold the interrupting arc by magnetic means away from said venting means during relatively high instantaneous values of arcine current, the arrangement being such that during relatively low instantaneous values of arclng current. the interrupting arc will be carried by the fluid flow created by a pressure-generating arc towards said venting means to effect its rapid extinction.

Another object is to provide an improved arcextinguishingstructure in which a pressure-generating are and an interrupting arc are established with suitable passage means between said arcs, and also to provide magnetic means for controlling the lateral movement of `the interrupting 'arc as a function of the instantaneous value of arcing current.

Another object of the present invention is to disturb the interrupting arc as little as possible during the peak of the alternating-current wave while bringing into play during relatively low instantaneous values as the arcing current approaches zero effective flow conditions in conjunction with suitable constrictions to extinguish said interrupting are. It will, however, be read ily apparent that numerous features of the present invention are applicable to circuit interrupters operating on direct-current systems as well as on alternating-current systems.

Another object is to provide an improved circuit interrupter in which an arc is drawn within a passage and a plurality of inwardly flowing streams of fluid are directed toward the are laterally against the side thereof and one or more venting passages are provided along the passage substantially at right angles tov the direction of the inwardly flowing streams of fluid.

Another object is to provide animproved circuit interrupter as set forth in the preceding paragraph in which the laterally iiowing streams of iluid are provided in pairs wherein each pair is positioned on substantially diametrically opposite sides of the are stream and the venting passages are disposed substantially at right angles to both of the streams of inwardly flowing fluid which constitute one of the aforesaid pairs.

Another object is to provide an improved circuit interrupter of the foregoing type in which magnetic means are provided to effect a lateral movement of the arc away from the one or more venting passages as a function of the instantaneous value of the arcing current, so that during the peak of the alternating-current wave, the arc is disturbed as little as possible to thereby minimize the over-all liberation of arc energy.

Another object is to provide an improved circuit interrupter of the type establishing both a pressure-generating arc and an interrupting arc in which improved passage means are utilized connecting the pressure-generating chamber and the interrupting chamber. Preferably, in conjunction with such a structure, improved venting means are disposed and magnetic means are provided to eiiect lateral movement of 'the interrupting arc as a function of arcing current to thus bring about as little disturbance of the arc during thepeak'cf the alternating-current wave as possible.

The term "fluid," as used in the specification and in the appended claims, includes gases, liquids and vapors.

It will be readily apparent to one skilled in the art that our invention is applicable to circuit interrupters operating in gaseous mediums, such as air, as well as in liquid mediums. However. for purposes of illustration, and not by way of limitation, we illustrate our invention as applied to circuit interrupters of the liquid immersed type.

Further objects and advantages will readily become apparent upon a reading of the following specification, taken in commotion with the drawings, in which:

Figure 1 is an elevational view, partly in cross section, of a circuit interrupter embodying our invention;

Fig. 2 is an enlarged fragmentary vertical sectional view of one of the arc-extinguishing structures shown in Fig. 1;

Fig. 3 is a sectional view taken along the line III-III of Fig. 2: and

Figs. 4 through 9 are detailed views of the plate structure employed in building up an arc-extinguishing structure of the type shown in Fig. 2.

Referring to the drawings, and more particularly to Fig. 1, the reference numeral I designates a tank filled with a suitable arc-extinguishing liquid 2, such as oil, in which are immersed a plurality, in this instance two, arc-extinguishing structures 3 supported by the two stationary contact structures 4 and the insulating bushings 5 in a conventional manner. An insulating operating rod 6, carrying at its lower end a ccmducting bridging member 1, is adapted for longitudinal reciprocating motion through the cover 8 of the tank,| and operated by an external operating mechanism, not shown, to effect the opening and closing of the circuit interrupter. It will be apparent that the circuit interrupter is connected into the external circuit by the line terminals 9. Hence, the electrical circuit through the interrupter consists briefly of the left-hand line terminal 9, the left-hand stationary contact structure 4, the conducting bridging member 1, the right-hand stationary contact structure 4 and the right-hand line terminal 9, as viewed in Fig. 1.

The dot and dash lines designated by the reference numeral I0 indicate the position of the conducting bridging member 'I when the circuit interrupter is in the open circuit position.

In the interrupter shown in Fig. 2, a pressuregenerating arc is drawn between the stationary contact 18 and the upper contacting portion 19 of the intermediate contact structure generally designated by the reference numeral 80. The intermediate contact structure 88 comprises a U-shaped bracket 8| rigidly secured .to a metallic support plate 82 by screws, not shown. The U-shaped bracket 8| serves as an upper seat for a compression spring 84. the lower end of which is seated in a recess 85 provided in the intermediate contact 86 to biasl the latter toward its lower position. The right-hand end of the intermediate contact 86 is pivotally mounted by a pin 81 which is movable in slots 8B provided in two upstanding brackets 89 also rigidly secured to the metallic support plate 82. The movable contact I3 engages a lower contacting portion 90 of the intermediate contact 86.`

Referring to Fig. 2, which shows the interrupter in the closed 'circuit position, it will be apparent that downward motion of the movable contact I3 will result in the intermediate contact 86 pivoting about the stationary contact 18 as a iirst ful-- crum point while the pin 81 moves down in the slots 88 by the biasing action exerted by the compression spring 84. This movement continues until the pin 81 reaches the lower end of the slots 88, at which time the intermediate contact 86 rotates in a counterclockwise direction about the pin 81 as a second fulcrum point. When the intermediate contact 86 has rotated suiliciently in a counterclockwise direction about the pin 81 so that it strikes the metallic support plate 82, continued downward movement of the movable contact I3 draws an interrupting arc in the interrupting chamber 95.

It will be observed that with the intermediate contact structure 80 shown, there is no need for exible shunts, a rolling action between the contact surfaces prevents welding, and a single compression spring 84 provides vnot only a biasing means to bias the intermediate contact structure 80 to its open circuit position, but also provides 4 contact pressure for the contacts in the closed circuit position. It will further be noticed that in the intermediate contact structure shown, the construction is such that the motion of the intermediate contact substantially prevents iiuid flow between the pressure-generating chamber and the interrupting chamber otherthan by the fluid conduits hereinafter to be described.

For example, in Fig. 2, the lower contacting portion 98 substantially iills the slot 92 provided in the insulating partition 93 separating the pressure-generating chamber 94 from the interrupting chamber 95.

The intermediate contact construction 88 described above is set forth and claimed in our copending application Serial No. 458,660, previously referred to.

Fig. 3 shows, together with Fig. 2, the construction of the interrupting chamber 95. Two longitudinal passages |23 are provided through the insulating partition plate 93. The two longitudinal passages |23 (see Fig. 3) are provided by alignment of apertures |25 provided in the several insulating plates forming the lower portion of the grid structure. Fig. 8 illustrates the type of insulating insert plate which may be used in our improved construction and is represented by the reference numeral I 24. The insulating insert plate |24 has openings |25 to form the passages |23 shown in Fig. 3. Insulating plate |24 also contains apertures 34 to accommodate the insulating studs 26, an elongated slot II3 and a constriction |I4. An insert |26 composed of a suitable magnetic material, in this instance iron, is formed to such a shape as to accommodate the openings |25. Immediately above and below the insulating insert plate |24 is an insulating guard plate |21, the conguration of which is more clearly shown in Figs. 6 and 7. The insulating guard plate |21 contains apertures 34 for the in sulatingstuds 26; openings |25, an elongated slot I I3 and a constriction I I4. The insulating guard plate |21 protects the insulating insert plate |24 from the effect of the interrupting arc. Immediately adjacent to each insulating guard plate |21 is an insulating ow plate |28, the conguration of which is more clearly shown in Figs. 4 and 5. This insulating ow plate |28 contains flow passages |29 which lead from the openings |25 to the enlarged slot II8. The plate |28 also has a constriction at II9 leading into the ent passage |20.

It will be apparent that during the opening iperation, downward movement of the operating rod 6 will cause downward movement of the movable contact I3 to thereby permit the compression spring 84 to force the intermediate contact in a clockwise direction about the stationary contact 18 as a rst fulcrum point. This clockwise rotation of the intermediate contact 86 continues until the pivot pin 81 strikes the bottom of the slots 88 at which time counterclockwise rotation of the intermediate contact 86 about the pivot pin 81 as a second fulcrum point takes place, thereby drawing a pressure-generating are between the contacts 18, 19 in the pressure-generating chamber 8 This pressure-generating arc will react upon the oil contained within the pressure-generating chamber 94 to cause the formation of considerable pressure therein.

The counterclockwise rotation of the intermediate contact 86 about the pivot pin 81 as a second fulcrum point continues until the intermediate contact 86 strikes the metallic support l plate l2. at which time continued downward movement of the movable *intact I3 causes an interrupting arc to be drawn between the top of the movable contact Il and the'contacting portion Il of the intermediate contact Il.

Thus the pressure-generating arc is drawn prior to the formation of the interrupting arc so that when the latter is drawn, it will be sub- Jected to inwardly flowing streams of fluid passing through the ilow passages |29.

From the foregoing description, it will be apparent that the oil will flow downwardly through the passages |28 and only the flow plates |28 will permit flow into the enlarged slot lil provided in the flow plates |28. During the peak of .the alterhating-current wave, the interrupting arc will be drawn to the left, as viewed in Fig. 3, to a position where the ilow coming through the dow passages |2l inthe flow plates III (see Fig. 4) interferes very little with the continuity of the interrupting arc. This reduces thearc energy and internal pressure in the arc-extinguishing. structure. When, however. the instantaneous value of arcing current decreases to a relatively low value, the magnetic inserts |28 will exert little biasing force on the interrupting arc and will permit it to return to the place where it was initially drawn. that is, between the opposed flow passages |29 (see Fig. 3) at which position it receives the full effect of a transverse flow of oil which tends to carry the interrupting arc to the right, as viewed in Fig. 3, to the constriction I4, the flow converging on the interrupting arc in this position as defined by the narrow portion I I8 in the flow plates |28. The strong deionizing action in the aro space effectively builds up dielectric strength at current zero so that the arc cannot restrike, thus interrupting the circuit.

From the foregoing description, it will be apparent that we have provided an improved fluid passage arrangement leading into the arcing passage Il, of elongated configuration. The oil duct arrangement of leading oil into the arcing passage !5 from the opposite sides thereof has the following advantages:

1. The left-hand end of the arcing passage 9B, as viewed in Fig. A2, is free of flow conditions to thereby permit the magnetic field to pull the interrupting are back into this left-hand end of the arcing passage I5 during relatively high instantaneous values of arcing current. I

2. The opposed double ducts |29 tend to center the interrupting arc in the slot and thus reduce burning of the ber walls of the arcing passage 95. In other words, should only the ducts be provided on one side of the arcing passage 85. this would tend to force the interrupting arc over against the opposite side of the arcing passage 95 and, hence, cause a burning of the walls of the arcing passage. By having the pairs of inlet passages |29, as contrasted with inlet passages disposed only1 on one side of the arcing passage, the arc is centered in the slot and thus burning of the ber walls is practically negligible.

3. By having the opposed fluid inlet passages |29 provided in pairs spaced at diiferent levels along the arcing passage 95 and of the same unit construction, that is the plates repeating along the stack, there thereby results similar interrupting action to each inch of arc length. Such a repeated plate construction is highly suitable to adjusting the number of units to the voltage rating oi the interrupter. Consequently, for-a high voltage rating of the interrupter, a larger number of the units would be employed than would interrupter.

be employed for a reduced voltage rating of the It will also be apparent from y the foregoing descrlption,

that by having the venting take place yat right angles to the direction of the inlet flow,

there results considerable turbulence in the arcing passage Il which is conducive to deionize-` tion of the arc space.

It will be observed that the two substantially parallel iirst fluid conducting passages |23 extend in a direction substantially parallel to the direction assumed by the interrupting arc, and that the one or more second pairs of fluid conducting passages |28 extend substantially transversely of the first uid conducting passages and lead toward the interrupting arc. The rst fluid conduits |23 terminate at their upper end within the pressure-generating chamber 94, and connect at their lower end with the one or more inlet passages III. The interrupting arc is elongated in a direction substantially parallel to the direction of the first uid conducting passages |22. I'he one or more third venting passages |20 communicate at one end with the region exterior of the arc-extinguishing unit 3, and terminate at their other end adjacent the interrupting arc to permit the venting of fluid therefrom.

It will be observed from the disclosed arrange ment, that the pressure-generating chamber 94 is disposed at the upper end of the unit 3 and that the elongated arcing passage 95 is disposed at the other end of the unit into which a plurality of pairs of inlet passages |29 lead at a plurality of points along the length thereof. We have. provided conduit means for interconnecting the pressure-generating chamber 94 with the plurality of pairs of inlet passages |29 so that the iluid may be forced from the pressure-generating chamber through the pairs of inlet passages |29 into the elongated arcing passage 95.

Thus, a plurality of pairs of opposed fluid inlet passages |29 lead into the arcing passage 95 at different levels along the arcing passage, and a plurality of vent passages |20, spaced axially Aalong the arcing passage 95, lead out of the arcing passage. Such a construction increases turbulence within the arcing passage and subjects the entire length of the interrupting arc to deionizing activity. Thus, we provide means for impinging a plurality of pairs of opposed jets of fluid at the arc at different levels along the length of the arc. A

An advantage of ou1 invention is the fact that by using a rectangularly-shaped contact I3, the arc is able to move to one end or the other end of the top surface of the rectangular contact i3. Thus, during the peak of the alternating-current wave when the lower terminal of the arc is moved to the left-hand end of the rectangular contact i3, as viewed in Fig. 3, there is permitted facilitated venting between the opposed inlet passages |28 and the ,vent passages without disturbing the arc core substantially at this time. On the other hand, during relatively low instantaneous values of arcing current, the lower terminal of the arc is enabled to move to the righthand end of the rectangular contact i3 to'be in the direct path of the oil flowout of the axially spaced vent passages I I l.'

Thus, by utilizing a rectangularly-shaped contact il, the interrupting action is improved as a result of facilitated movement of the lower are terminal and there is more free venting in bypassing the are during the peak of the alternating-current wave.

It wui be apparent to one sinned m the art that our invention is readily applicable not only to liquid I:immersed circuit interrupters but also to i circuit interrupters operated in a gaseous medium, such as air. The insulating plates described in connection with the embodiment of our invention may be made of a suitable gas evolving material to facilitate the interruption of the interrupting arc. Consequently, the interrupter previously described could be operated in air with the insulating plates composed of a suitable gasevolving material such as horn fiber or boric acid. Merely for purposes of illustration, and not by way of limitation, we have described our invention as embodied in an oil immersed circuit interrupter.

Although we have shown and described a specific structure, it is to be understood that the same was only for purposes of illustration and that changes and modifications may be made therein by those skilled in the art Without departing from the spirit and scope of the appended claims.

We claim Vas our invention:

1. In a circuit interrupter, means at least partly of insulating material dening an elongated substantially closed arcing chamber, means for establishing an arc axially within said chamber, means defining a pair of opposed flow passages on substantially the same plane leading into the chamber laterally thereof, means other than the aforesaid arc for positively forcing fluid through the flow passages and into engagement with the arc, and means defining a vent passage leading out of the chamber and disposed substantially at right angles to the direction of entrance of the now passages and also in a plane substantially parallel to the plane of the flow passages.

2. In a circuit interrupter, means at least partly of insulating material defining an elongated arcing chamber, means for establishing an arc axially within said chamber, means defining a pair of oppositely disposed iiow passages leading into the chamber laterally thereof in substantially the same plane, means other than the aforesaid arc for forcibly driving arc extinguishing fluid through the opposed flow passages in opposite direction, and means defining a relatively restricted vent passage leading out of the chamber A disposed substantially at right angles to the direction of entrance of the flow passages and in a plane substantially parallel to the plane f the opposed flow passages.

3. In a circuit interrupter, means at least partly of insulating material dening an elongated arcing slot, means for establishing an arc axially within the slot, means defining a flow passage leading into the slot laterally thereof, means defining a vent passage leading out of the slot and disposed substantially at right angles to the direction `of entrance of the flow passage, and means for moving the arc laterally away from the vent passage during the peak of the alternatingcurrent wave.

4. In a circuit interrupter, means at least partly of insulating material defining an elongated arcing slot, means for establishing an arc axially within the slot, means defining a pair of oppositely disposed flow passages leading into the slot laterally thereof, and means defining a vent passage leading out of the slot and disposed Y substantially at right angles to the direction of entrance of the flow passages, and means for moving the arc laterally away from the vent pas- .tablishing an interrupting arc within said arcing slot, two opposed liquid passages leading from said pressure-generating chamber into said arcing slot for transmitting liquid into said arcing slot and toward said venting means, and a plurality of U-shaped plates of magnetic material straddling said arcing slot to bias said interrupting arc during relatively high instantaneous values of arcing current away from said venting means so that said interrupting arc is not ail'ected by the flow of liquid through said opposed liquid passages.

6. In a circuit interrupter, means for drawing an arc, means for directing a pair of opposed fluid streams at the arc from substantially opposite sides thereof, and venting means including a relatively restricted passage disposed substantially at right angles to the direction of flow of the uid streams and at substantially the same level as the inwardly directed fluid streams.

7. In a circuit interrupter, means for drawing an arc, vmeans for directing a pair of opposed fluid streams at the arc from substantially opposite sides thereof, venting means including a relatively restricted passage disposed substantially at right angles to the 'direction of ow of the fluid streams and at substantially the same level as the inwardly directed fluid streams, means for drawing a serially related arc, and means utilizing the pressure formed at the last-mentioned arc to force fluid under pressure through the secondmentioned means.

8. In a circuit interrupter, means for drawing an arc, means vat least partly of insulation for directing a plurality of pairs of opposed fluid streams at the arc from substantially opposite sides thereof, the pairs being spaced from each other in a direction axially of the are in different substantially parallel planes, and means defining a relatively restricted venting passage for each pair leading away from the arc in a plane substantially parallel to the aforesaid planes.

9. In a circuit interrupter, means for drawing an arc, means for directing opposed fluid streams at the arc from opposite sides thereof, and mag# netic means for moving the arc laterally out of the direct ow path of said uid streams during relatively high instantaneous values of arcing current.

10. In a circuit interrupter, a plate structure comprising a plurality of suitably shaped plates, the plates having openings therein which when aligned form an elongated arcing passage, means for establishing an arc axially within the arcing passage, one or more of the plates having embedded therein a U-shaped magnetic insert to bias the arc laterally within the arcing passage. one or more of the plates having an inlet passage leading laterally into the arcing passage, and one or more of the plates having a vent passage leading laterally out of the arcing passage at right angles with respect to said inlet passage.

11. In a circuit interrupter, a plate structure comprising a. plurality of suitably shaped plates, the plates having openings therein which when aligned form an elongated arcing passage, means for establishing an arc axiallywithln the arcing 9 l passage, one or more oi' the plates having em bedde therein a U-shaped magnetic insert to bias t e arc laterally within the arcing passage,

one or more ci the platea having a pair of opposed inlet passages leading laterally into the arcing passage substantially" on opposite sides of the arc, and one or more of the plates having a vent passage leading laterally out of the arcing passage at right angles with respect to said inlet passage.

12. In a circuit interrupter, a plate structure comprising a plurality oi' suitably shaped plates, the plates having openings therein which when aligned form an elongated arcing passage, means for establishing an arc axially within the arcing passage, one or more oi the plates having embedded therein a U-shaped magnetic insert to bias the arc laterally within the arcing passage, one or more of the plates having a pair of opposed inlet passages leading laterally into the arcing passage substantially on opposite sides of the are, and each of the latter-mentioned plates having a vent passage leading laterally out of the arcing passage disposed substantially at right angles to the direction of the inlet passages.

13. In a circuit interrupter, a plate structure comprising a plurality of suitably shaped plates, the plates having openings therein which when aligned form an elongated arcing passage, means for establishing an arc axially within the. arcing passage, one or more of the plates having embedded therein a U-shaped magnetic insert to bias the arc laterally within the arcing passage, one or more of the plates having an inlet passage leading laterally into the arcing passage, one or more oi' the plates having a vent passage leading laterally out of the arcing passage substantially at right angles to said inlet passages, means for forming a serially related arc. and the pressure formed about the serially related arc forcing iluid under pressure through the one or more inlet passages toward the mst-mentioned arc.

14. In a circuit interrupter, a plate structure comprising a plurality of suitably shaped plates, the plates having openings therein which when aligned form an elongated arcing passage, means for establishing an arc axially within the arcing passage, one or more of the plates having embedded therein a U-shaped magnetic insert to l bias the arc laterally within the arcing passage,

one or more of the plates having a pair of opposed inlet passages leading laterally into the arcing passage substantially on opposite sides of the arc, one or more oi the plates having a vent passage leading laterally out of the arcing passage substantially at right angles tosaid inlet passages, means for forming a serially related are, and the pressure formed about the serially related arc forcing iuid under pressure through the one or more inlet passages toward the firstmentioned arc.

15. In a circuit interrupter, an arc-extinguishing unit, means for establishing a pressure-generating arc, two substantially parallel first iiuid conducting passages, means for establishing an interrupting arc and elongating it in a direction substantially parallel to the direction of the irst nuid conduclng passages and intermediate them, one or more second nuid conducting passages associated with each first iluld conducting passage extending substantially transversely oi the nrst fluid passages and leading toward the interrupting arc, the pressure-generating arc forcing iluid under pressure through the two ilrst nuid conducting passages andalso through the two gaat.

or more second fluid conducting passages toward the interrupting are to effect its extinction, and one or more third venting passages communicating at one end with the region exterior oi' the unit and terminating at their other end adjacent the interrupting arc to permit the venting oi' uid therefrom.

18. In a circuit interrupter, means denning a pressure-generating chamber, means dening an l0' elongated interrupting passage. means for establishing a pressure-generating arcwithin the pressure-generating chamber, means for establishing an interrupting arc within the interrupting passage, a pair of uid conduits parallel to the interrupting passage and terminating at one end at the pressure-generating chamber, one or more inlet passages leading from each iiuid conduit into the interrupting passage and ne or more relatively restricted venting passages leading from said interrupting passage substantially at right angles to he direction of said inlet passages. i

17. In a circuit interrupter, an arc-extinguishing unit, means forming a pressure-generating chamber, a pressure-generating contact cooperable with an intermediate contact to establish a pressure-generating arc within the pressuregenerating chamber, means forming an interrupting passage, a movable contact cooperable with the intermediate contact to establish an interrupting arc within the interrupting passage, means forming two substantially parallel rst fluid conducting passages extending in a direction substantially parallel to the direction assumed by the interrupting arc, one or more second fluid conducting passages extending substantially transversely of the first fluid. passages and leading toward the interrupting arc and one or more relatively restricted venting passages leading from said interrupting passage substantially at right angles to the dirction of said inlet passages.

18. In a circuit interrupter, an arc-extinguishing unit. means denning a pressure-generating chamber disposed at one end of the unit, means defining an elongated arcing passage disposed at the other end of the unit, a plurality of pairs of inlet passages leading into the arcing passage on opposite sides thereof at a plurality of points along the length of the arcing passage in substantially parallel planes. and conduit means for interconnecting the pressure-generating chamber with the plurality of pairs of inlet passages so that fluid may be forced from the pressure-generating chamber through the pairs of inlet passages into the arcing passage and venting means arranged to withdraw iluid from said arcing passage substantially at right angles to said inlet passages and in one or more planes substantially parallel to the aforesaid planes.

19. In a circuit lnterrupter, means denlng an elongated arcing passage, means dening a plurality of pairs of opposed uid inlet passages leading into the arcing passage yat different levels along the arcing passage, and a plurality of relatively restricted vent passages spaced axially along the arcing passage rleading out of the arcing passage.

20. In a circuit interrupter, an arc-extinguishing unit, means forming a pressure-generating chamber, a pressure-generating contact cooperable with an intermediate contact to establish a pressure-generating arc within the pressuregenerating chamber, means forming an interrupting passage, a movable contact cooperable with the interrnediate contact to establish an interrupting arc within the interrupting passage. means forming two substantially parallel rst fluid conducting passages extending in a direction ,substantially parallel to the direction assumed by the interrupting are, one or more second iluid conducting passages extending substantially transversely of the rst iluid passages and leading toward the interrupting arc, and one or more third fluid conducting passages substantially at right angles to said second fluid conducting passages permitting a venting of fluid from the interrupting arc to the region exterior of the unit.

21. In a circuit interrupter, an arc-extinguishing unit, means for establishing a pressure-gen erating arc, two substantially parallel first uid conducting passages, means for establishing aninterrupting arc and elongating it in a direction substantially parallel to the direction of said rst fluid conducting passages and intermediate them, one or more second uid conducting passages extending substantially transversely of said first REFERENCES CITED The following references are of record in the file of this' patent:

UNITED STATES PATEN'rs '15 Number Name Date 1,899,612 Dyer Feb. 28, 1933 1,902,507 Juhlin Mar. 21, 1933 1,991,901 Leeds Feb. 19, 1935 2,067,648 Reher Jan. 12, 1937l 20 2,080,612 Kesselring et al May 18, 1937 2,081,830 Merriam May 2 5, 1937 2,385,008 Leeds et al Sept. 15, 1945 2,403,103 Leeds July 2, 1946 

